Heavy Ion-induced DNA Double-strand Breaks in Yeast

Abstract

DNA double-strand break (dsb) induction in diploid yeast was measured by neutral sucrose sedimentation after exposure to very heavy ions with values of linear energy transfer (LET) ranging from about 300 to 11500 ke V/µm. Linear fluence dependencies were found in all cases from which dsb production cross-sections (σ_dsb) could be calculated. Corresponding cross-sections for cell killing ((σ_i) were derived from final slopes of survival curves measured in parallel and for the same fluence range. A close correlation was found between σ_i and σ_dsb. It is calculated that over the entire LET range, including 30 Me V electron irradiation, about 22 dsb are induced per lethal event when high exposures are considered.